release version 9.0

Problem:    About time to release Vim 9.0.
Solution:   Update the version number everywhere.
diff --git a/runtime/doc/netbeans.txt b/runtime/doc/netbeans.txt
index 7f69376..241fdb7 100644
--- a/runtime/doc/netbeans.txt
+++ b/runtime/doc/netbeans.txt
@@ -1,4 +1,4 @@
-*netbeans.txt*  For Vim version 8.2.  Last change: 2022 Apr 03
+*netbeans.txt*  For Vim version 9.0.  Last change: 2022 Apr 03
 
 
 		  VIM REFERENCE MANUAL    by Gordon Prieur et al.